U2 has hidden an incredibly cryptic reference to a biblical passage on the cover of their album, "All That You Can't Leave Behind". What you need to do to view the message is look at the cover. On the cover, there's the four members of U2 standing around. In the background, on the left, on the ceiling of the place they are standing is a sign saying "J33-3". U2 altered the photo to say this. What it is is a coded reference to the book of Jeremiah, Chapter 33, verse 3. The passage reads, "'Call to me and I will answer you and will tell you great and hidden things which you have not known.' Interesting passage and fits in to with the point of this site!